The present invention relates to semiconductor packaging in general and more specifically to a lead frame and a method of packaging a semiconductor device using such a lead frame.
Wire bonding is widely used in semiconductor packaging to provide electrical connection between an integrated circuit (IC) die and a lead frame. In wire bonding applications, wire loops are formed between the die pads of an IC die and the lead fingers of a lead frame. Typically, first wire bonds are formed on respective ones of the die pads, and second wire bonds are formed on the corresponding terminals. Wire loops with a steep angle of approach to the second wire bond are required in certain applications, for example, to prevent damage during a singulating operation to separate the lead fingers from the die receiving area of the lead frame. Such loop profiles are created by forming a high tail kink in the bond wire, that is, a bend in the tail end of the bond wire at a substantial vertical spacing from the second wire bond. However, because the bond wire is less rigid further away from the first wire bond, it is difficult to shape the tail end of the bond wire. Hence, the loop profiles of bond wires with tail kinks are often inconsistent. The tail kink is sometimes formed too low and the corresponding wire loop is susceptible to damage during subsequent packaging steps.
In view of the foregoing, it is desirable to form a wire bonded semiconductor device with consistent loop profiles. More particularly, it is desirable to form a semiconductor device wherein the bond wires have tail kinks formed at a predetermined height.